Abstract
BACKGROUND CONTEXT: Failure to accurately predict length of stay (LOS) and discharge disposition in the setting of spine fusion episodes of care can have substantial impact on patient care and resource allocation. Mandatory upcoming bundled payment models for spinal fusion will focus solely on traditional Medicare (TM) beneficiaries; however, less is known about episode of care metrics in this subgroup compared with patients in other insurance classes.
PURPOSE: We sought to compare time-based trends among TM and Medicare Advantage (MA) in (1) LOS and home discharge, (2) readmission and emergency department visits, and (3) prevalence of medical comorbidities and social vulnerability.
STUDY DESIGN/SETTING: The Epic Cosmos dataset (comprising longitudinal records for over 300 million patients from over 1,700 hospitals) was used for this retrospective cohort study.
PATIENT SAMPLE: Episodes of care containing single-level lumbar fusions performed in adults between January 1st, 2016, to December 31st, 2024.
OUTCOME MEASURES: The primary outcome was LOS in days. Secondary outcomes included rates of discharge home, 30-day readmission rates, and 30-day emergency department visits.
METHODS: Time-based trends and differences among primary insurance classes in LOS were assessed via a negative binomial regression model that included a 2-way interaction between primary insurance class and time, with adjustment for sociodemographic, clinical, and institutional covariates. Primary insurance classes included TM, MA, Commercial, and Medicaid. Post-hoc tests were adjusted for multiple comparisons via the Holm-Bonferroni method.
RESULTS: Among 126,304 spinal fusion episodes, LOS for TM patients decreased at an adjusted rate of 1.1% ([95% CI 0.4, 1.7], p<.001) faster per year compared with MA (TM: 2016-2024 unadjusted LOS 3.37-2.54; MA 3.53-3.12 days). Between 2016 and 2024, TM and MA both saw increases in home discharge, however by 2024 MA had higher adjusted rates of home discharge (unadjusted 2016-2024 raw rates TM 77.2%-86.8%; MA 76.0%-87.9%; adjusted 2024 rate 33% higher than TM [95% CI 18%, 51%, p<.001]). Over the study period, the MA cohort changed to become the group with the greatest number of Hierarchical Conditional Categories (2016 to 2024, 0.45-0.77; 15% increase compared to TM [10%, 22%, p<.001]). At the end of the study period, TM and Commercial had similar social vulnerability index (SVI) (unadjusted 50th vs. 50th percentile, adjusted p>.05) and MA and Medicaid had similar SVI (unadjusted 56th and 63rd percentile, adjusted p>.05). There were no differences in time-based trends between groups for readmission rates and emergency department visits.
CONCLUSIONS: We observed longer LOS and increased home discharge rates with MA compared to TM over time without apparent improvements in readmission rates or emergency department visits. TM now has LOS and SVI approximating the commercially insured. The changes demonstrated in this study underscore widening gaps between TM and MA beneficiaries, despite the fact that upcoming mandatory bundled payment models will focus solely on TM beneficiaries. As MA becomes the dominant insurance class in the geriatric population, spine surgeons should be aware of patterns specific to MA patients, such as prolonged LOS and increasing denials for postacute care. Clinicians play a key role in setting patient expectations at the point-of-care and presurgical discharge planning may be important for certain subgroups.
LEVEL OF EVIDENCE: III.